Overview

Port mappings allow containers to access ports on the host container
instance to send or receive traffic. Port mappings are specified as
part of the container definition.

If using containers in a task with the awsvpc or host network
mode, exposed ports should be specified using containerPort. The
hostPort can be left blank or it must be the same value as the
containerPort.

After a task reaches the RUNNING status, manual and automatic host
and container port assignments are visible in the networkBindings
section of DescribeTasks API responses.

Instance Attribute Details

#container_port ⇒ Integer

The port number on the container that is bound to the user-specified
or automatically assigned host port.

If using containers in a task with the awsvpc or host network
mode, exposed ports should be specified using containerPort.

If using containers in a task with the bridge network mode and you
specify a container port and not a host port, your container
automatically receives a host port in the ephemeral port range (for
more information, see hostPort). Port mappings that are
automatically assigned in this way do not count toward the 100
reserved ports limit of a container instance.

#host_port ⇒ Integer

The port number on the container instance to reserve for your
container.

If using containers in a task with the awsvpc or host network
mode, the hostPort can either be left blank or set to the same
value as the containerPort.

If using containers in a task with the bridge network mode, you
can specify a non-reserved host port for your container port
mapping, or you can omit the hostPort (or set it to 0) while
specifying a containerPort and your container automatically
receives a port in the ephemeral port range for your container
instance operating system and Docker version.

The default ephemeral port range for Docker version 1.6.0 and later
is listed on the instance under
/proc/sys/net/ipv4/ip_local_port_range; if this kernel parameter
is unavailable, the default ephemeral port range from 49153 through
65535 is used. You should not attempt to specify a host port in the
ephemeral port range as these are reserved for automatic assignment.
In general, ports below 32768 are outside of the ephemeral port
range.

The default ephemeral port range from 49153 through 65535 is always
used for Docker versions before 1.6.0.

The default reserved ports are 22 for SSH, the Docker ports 2375 and
2376, and the Amazon ECS container agent ports 51678 and 51679. Any
host port that was previously specified in a running task is also
reserved while the task is running (after a task stops, the host
port is released). The current reserved ports are displayed in the
remainingResources of DescribeContainerInstances output, and a
container instance may have up to 100 reserved ports at a time,
including the default reserved ports (automatically assigned ports
do not count toward the 100 reserved ports limit).